Vector whose elements add up to a value in R -


i'm trying create vector elements add specific number. example, let's want create vector 4 elements, , must add 20, elements 6, 6, 4, 4 or 2, 5, 7, 6, whatever. tried run lines using sample() , seq() cannot it.

any appreciated.

to divide 4 parts, need 3 breakpoints 19 possible breaks between 20 numbers. partitions sizes of intervals between 0, partitions, , 20:

> sort(sample(19,3)) [1]  5  7 12 > diff(c(0, 5,7,12,20)) [1] 5 2 5 8

test, lets create big matrix of them. each column instance:

> trials = sapply(1:1000, function(x){diff(c(0,sort(sample(19,3)),20))}) > trials[,1:6]      [,1] [,2] [,3] [,4] [,5] [,6] [1,]    3    1    8   13    3    2 [2,]    4    7   10    2    9    5 [3,]    2   11    1    4    3    7 [4,]   11    1    1    1    5    6

do add 20?

> all(apply(trials,2,sum)==20) [1] true

are there weird cases?

> range(trials) [1]  1 17

no, there no zeroes , nothing bigger 17, (1,1,1,17) case. can't have 18 without zero.


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